Lymphoma stem cells: enough evidence to support their existence?

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Leukemia stem cells are crucial for leukemia development, but the cell of origin for B-cell lymphomas remains debated.
• Understanding the initiating cells is key to deciphering lymphoma pathogenesis and developing targeted therapies.

Purpose of the Study:

• To propose and delineate the cellular origins of various B-cell non-Hodgkin's lymphomas (B-NHLs).
• To differentiate the cell populations initiating follicular lymphoma (FL), mantle cell lymphoma (MCL), diffuse large B-cell lymphoma (DLBCL), and sporadic Burkitt's lymphoma (sBL).

Main Methods:

• Conceptual modeling based on existing knowledge of V(D)J recombination, immunoglobulin gene translocations, and B-cell differentiation.
• Analysis of proposed cooperating mutations and epigenetic modifications driving malignant transformation.
• Discussion of stem cell-like properties in different B-cell populations and their role in lymphoma initiation.

Main Results:

• Committed lymphoid progenitor/precursor cells with active V-D-J recombination are proposed as initiating cells for FL and MCL, requiring secondary mutations for full transformation.
• DLBCL and sBL are proposed to originate from B lymphocytes in the germinal center acquiring translocations via IG-hypermutation or class-switching errors.
• Certain B-cell populations (centroblasts, memory B cells) or lymphocytes with MYC rearrangements may bypass the need for secondary mutations.

Conclusions:

• Different B-cell non-Hodgkin's lymphomas likely arise from distinct cell populations at different stages of B-cell development.
• Aberrant epigenetic modifications may also initiate lymphoma development by conferring stem-cell features or reprogramming lymphocytes.
• Identifying and characterizing these lymphoma-initiating cells is crucial for advancing our understanding of B-NHL pathogenesis and therapy.